Classic Computer Magazine Archive COMPUTE! ISSUE 139 / APRIL 1992 / PAGE 6

PC Jargon Made Easy
by Robert Bixby, Clifton Karnes, Joyce Sides


ASCII. American Standard Code for Information Interchange. ASCII is a standard for relating numbers to alphanumeric characters and symbols. Standard ASCII is a 7-bit code, which means there are 128 possible values. The first 128 symbols in the PC's character set are standard ASCII. The next 128 characters are specific to the PC and are often referred to as the extended character set.

bandwidth. Although this is technically the frequency range of a communications channel, it is often used as a relative measure of a channel's capacity to transfer information. The greater the capacity, the greater the bandwidth. For example, a 16-bit bus has greater bandwidth than an 8-bit bus.

CD-ROM. Compact Disc-Read Only Memory. CDs have been popular for several years as the medium of choice for sound recording, and they're fast becoming an important medium for storage for computers. Although the CD's optical technology doesn't easily lend itself to erasing and rewriting, its huge capacity (about 600MB) makes it invaluable for storing large amounts of data.

command line. The DOS command line is the familiar A> prompt. When you type commands at the prompt, the command interpreter, COMMAND.COM, executes them or tells you their syntax is incorrect.

compiler. A compiler translates an entire file of source code into pure machine language. When you run a compiled program, the entire program loads into memory and executes.

CPU. Central Processing Unit. This is the computer's brain, which controls the machine's resources and manages calculations. In the PC, the CPU is a microprocessor chip from the Intel 80x86 family, which includes the 8088, 8086, 80286, 80386, and 80486. CPU is also used to refer to a PC's system box (the part of the machine that houses the CPU, memory, and disk drives).

DOS. Disk Operating System. Although it does much more than just manage disks, that's DOS's primary job. There are several varieties of DOS for PCs, including MS-DOS (Microsoft), PC-DOS (IBM), and DR DOS (Digital Research).

interpreter. An interpreter translates one line of source code at a time and executes it. BASIC is the most popular interpreted language, though modern BASICs can be compiled.

K. Kilobyte. A kilobyte is 1024 bytes. Early PCs came with 4K or less. The standard for 8088-based PCs is now 640K, for 80286s it's 1MB, and for 80386s it's 2MB or more. As with money, you can never have enough RAM.

MB. Megabyte. A megabyte is equal to 1,048,576 bytes, or 1,024K. Memory on large systems and storage for most hard disks are measured in megabytes.

MHz. Megahertz. A megahertz is 1,000,000 cycles per second. Megahertz is used as the measure of a microprocessor's speed. The first IBM PC ran at 4.77 MHz. The new 80386 and 80486 chips run at 33 MHz of faster.

multitasking. In modern parlance, multitasking means running two or more programs at the same time. On the PC, the Intel 286, 386, and 486 processors can multitask in protected mode. Windows 3.0, OS/2, GeoWorks Ensemble, DESQview, and Unix are examples of PC multitasking operating systems and operating system extensions.

RAM. Random Access Memroy. Athough this kind of memory can be accessed randomly, a better name would be read-write memory because you can both read from and write to any RAM memory location.

RAM disk. A RAM disk is an area of memory that functions just like a disk drive, except that it's lightning fast. To install a RAM disk on your PC, you put a command like DEVICE=RAMDRIVE in you CONFIG.SYS file.

ROM. Read Only Memory. Computer memory than can be read from but can't be changed or written to. In the PC, the BIOS (Basic Input/Output System) is ROM.

TSR. Terminate and Stay Resident. This is the name for a large class of applications that remain in your PC's memory and are called with hot keys. TSRs take advantage of two important DOS attributes. You can run a program but leave it in memory, and you can redirect system routines to your own code. The most popular early TSR was probably Sidekick. Recent superstar TSRs include PC Tools Deluxe Desktop.


address space. This is the amount of RAM a CPU can "see." An 8088 can address as much as 1MB, an 80286 as much as 16MB, and an 80386 as much as 4096MB of memory.

conventional memory. Conventional memory is simply the first 640K of memory. The 384K of memory between the 640K barrier and 1MB (called UMB, or upper memory) is reserved for DOS, but a portion of this memory can be accessed as expanded memory with the appropriate hardware.

EMS. Expanded Memory Specification. This is a specification developed by Lotus, Intel, and Microsoft (LIM) to break the 640K barrier by accessing up to 32MB of expanded memory. EMS maps a 64K page divided into four 16K windows in DOS's upper memory area (the 384K above 640K). Until the release of LIM version 4.0, multitasking was not available through the EMS standard.

expanded memory. Introduced in 1985 by the consortium of Lotus, Intel, and Microsoft, expanded memroy is a way to expand a PC or AT beyond 1MB of memory. The memory manager (a chip set that supervises expanded memory access) is given a handle by a program to tell it where some information lies in the memory above 1MB. When the request is made, the memory manager maps that portion of memory to four 16K regions in high memory for easy program access. The system works a little like a RAM disk with a maximum capacity of 8MB (with LIM EMS 3.2) or 32MB (with LIM EMS 4.0).

extended memory. Technically, extended memory is any memory beyond the base 1MB of memory accessible by the 80286 and the 80386 operating in real mode. An AT can access memory above 1MB directly through the use of a RAM disk. DOS provides the means of creating a RAM disk with device drivers such as VDISK.SYS and RAMDRIVE.SYS. Other uses for extended memory include disk caching and expanded memory emulation. Windows 3.0 directly accesses this memory.

HMA. High Memory Area. High memory is the first 64K of extended memory. By a quirk in the design of 80286 and 80386 processors, this memory is directly accessible in real mode.

LIM. Lotus-Intel-Microsoft. LIM is the acronym that stands for the developers of EMS (Expanded Memory Specification), which can allow any PC or AT operating in real mode to access up to 32MB of memory.

protected mode. Protected mode is a special multitasking feature of 80286, 80386, and higher CPUs. In this mode, your PC can run Windows 3.0, and it "sees" as much as 16MB of memory at a time, all of which is accessible. Protected mode also allows the 80286 and 80386 machines to access the hard disk as if it were RAM. DOS runs in real mode, not protected mode.

real mode. Real mode is the default for the 8088 and 8086 CPUs. The 80286 and 80386 CPUs are able to run as a fast 8088 chip (real mode) or as a multitasking 16-bit chip (protected mode). As an 8088-emulating chip, the 80286 and 80386 have the same memory limitations (1MB) as the 8088.

UMB. Upper Memory Block. The upper memory area is located between 640K and 1MB. IBM used to call this area reserved memory. Expanded memory managers and programs such as QEMM and 386MAX use this area, dividing it into blocks into which you can load TSRs and device drivers high.

XMS. eXtended Memory Specification. XMS provides a way of managing extended memory in much the same way as EMS 4.0 provides a way to manager expanded memory. It also allows access to the HMA. To use XMS, you need to install a device driver called HIMEM.SYS in your CONFIG.SYS file.


cache. A cache is a special program that uses part of your PC's RAM to store the information your disk uses most often. With a cache, when the system requests data from a disk, there's a good chance the dta (or part of it) will be in the cache. Since RAM access is much, much faster than disk access, a cache can make disk-intensive applications fly.

cluster. The File Allocation Table maps groups of sectors called clusters. A cluster is the minimum amount of storage space a file can use. For this reason, each file on a disk takes up at least one cluster. On 360K floppy disks, a cluster is two sectors or 1K. On an average hard disk, a cluster is four sectors or 2K.

FAT. File Allocation Table. The FAT is an area on a DOS disk that comes directly after the boot record. It contains information on all the sectors on the disk, and it maps the location of every file on the disk.

file attributes. Each file on a disk is marked as Read Only, Hidden, System, Archive, or a combination of these. These file attributes are located with the other file information in the directory. With DOS's ATTRIB command, you can alter a file's attributes.

floppy. Floppy disks are thin, round, flexible disks housed inside a 5 1/4-inch flat plastic housing. The sturdier 3 1/2-inch disks are also referred to as floppies.

ms. Millisecond. Milliseconds are commonly used to measure the speed of hard disk drives. Common speeds are 65 ms for a 20MB drive, 28 ms for a 40MB, and 14 ms for a 110MB. The smaller the number, the faster the drive.

partition. Hard disks are divided logically into one or more areas called partitions. Prior to DOS 4.0, if you had a hard disk larger than 32MB, you had to partition your drive with the DOS FDISK command. After partitioning, your drive will act as if it were two or more drives. The partition table is located on track 0 directly in front of the disk's boot sector.

root directory. After a disk's File Allocation Table comes the root directory. The root directory is like the table of contents. It stores the filenames, time and date stamp of latest update, starting cluster number, file size, and file attributes.

sector. Disks are divided in concentric circles called tracks, and each track is further divided into wedges called sectors. Sectors can be identified by the side of the disk they're located on, their track number, and the sector number within the track. Although sectors can be any size, on PCs they're almost always 512K.

subdirectory. Before the introduction of DOS 2.0, all the files on the disk had to reside in the root directory. The ability to create subdirectories solved this problem and made it possible to organize a disk. The root directory is like a drawer containing folders. The folders are subdirectories, which contain other folders or individual files.

track. Tracks form concentric circles beginning with track 0 at the outer edge of the disk. The denser the medium (that is, the more information it can hold), the closer the tracks are together. A 5 1/4-inch floppy disk has a density of 48 tracks per inch, or tpi; 3 1/2-inch floppies weigh in at 135 tpi.

volume label. When you format a disk, you have the option of giving it a name--a volume label. To give a floppy disk a volume label, use the /V option when you format.

wildcards. Wildcards are special characters that stand for other characters. DOS uses the question mark (?) and asterisk (*) as wildcards. The asterisk stands for any number of characters of any kind, and the question mark stands for one character of any kind. Wildcard patterns can be useful when you want to execute a DOS command on several files at once. To copy all the files on a disk or in a current directory to a hard drive or another disk, enter COPY * . * drive: at the DOS prompt.


CGA. Color Graphics Adapter. IBM introduced the CGA card as a way to bring color graphics to the PC. For its 320 x 200 pixel graphics screen, it added pink and powder blue to the already perfected black-and-white. CGA also provides a 640 x 200 pixel high-resolution graphics screen in black-and-white and text in 16 colors against a background that can be displayed in 8 colors.

EGA. Enhanced Graphics Adapter. A marked improvement over the CGA adapter, EGA can display 16 colors on a graphics screen of 320 x 200, 640 x 200, or 640 x 350 pixels. Although originally released in a configuration that only provided 16 colors on a 320 x 200 pixel screen, this limitation was overcome in response to consumer demands.

8514/A. The 8514/A graphics card introduced in 1987 with the PS/2 line of computers, provides an interlaced screen with a resolution of 1024 x 768 pixels. At this resolution, it provides 256 colors. Currently, it is only one of many ultra VGA designs trying to establish themselves as standards. Since the 8514/A hardware is expensive and very few programs make use of it, most users have been content with the various flavors of Super VGA.

EPS. Encapsulated PostScript. This object-oriented graphics format contains all the code necessary to print a graphics file on a PostScript printing device.

GIF. Graphic Interchange Format. This graphic standard was developed by CompuServe to provide a standard graphics format for online services. It is a compressed bitmapped format.

Hercules Graphics Adapter. The hercules Graphics Adapter, also known as the HGA, is a modification of the MDA standard that allowed the card to display very clean monochrome graphics at a resolution of 720 x 348 pixels as well as the crisp, clear character set of the MDA. This adapter dates from 1982. Interestingly, the Hercules Graphic Adapter was developed by Van Suwannukul so that he could write his doctoral thesis with the Thai alphabet.

IFF. Interchangeable File Format. IFF is a bitmapped format that's the standard graphics format on the Amiga and is also used on the PC by DeluxePaint.

interlaced. An interlaced screen is drawn twice. First it's drawn in one position, and then it's shifted about half a pixel and redrawn. Using this technique, it's possible to multiply the resolution of a monitor. In computers, the interlaced screen appears to jump slightly, as if it has the jitters. This makes it unacceptable for word processing and other detail work.

MCGA. Multi-Color Graphics Array. The MCGA was introduced to provide a colorful graphics display for the low-end PS/2 machines. It's capable of producing graphics of 320 x 200 pixels in 256 colors from a palette of 262, 144 colors.

MDA. Monochrome Display Adapter. Introduced with the PC in 1981, this display adapter could only display text, though the text it displayed was very clear. The reasoning behind this decision was that the PC was airmed at business users and business persons were not interested in displaying graphics. It failed to revolutionize computer graphics and was quickly supplanted by the Hercules Graphics Adapter as the monochrome adapter of choice. If it had been capable of displaying graphics, it would have displayed 720 x 350 pixels.

PCX. This is a standard bitmapped graphics format for the PC, developed by Z-Soft. Most PC paint programs support PCX, as do almost all bitmapped graphics applications. According to Z-Soft, PCX doesn't stand for anything, though Picture Exchange seems an obvious origin.

pixel. Picture element. A pixel is the smallest dot of color your video card can manage. Screens are defined by their dimensions in pixels.

resolution. Resolution refers to the number of pixels available to reproduce an image on the screen. The higher the resolution, the more pixels there are available. Curves produced in a low resolution like 320 X 200 have a stairstep appearance. They are obviously formed of short straight lines. A curve on a high-resolution screen will appear much smoother. Resolution is also used to describe printer dot density. Most laser printers can reproduce 300 dpi (dots per inch), making very smooth curves with only a few jaggies. A 300-dpi laser printer provides 90,000 dots per square inch. A 400-dpi laser printer can provide 160,000 dots per square inch, providing still higher resolution and smoother curves.

Super VGA. Super Vidio Graphics Arrays. This was an enhancement of the standard VGA that allowed an 800 X 600 pixel screen displaying 16 colors from a palette of 256. But barely was the standard set before manufacturers began to depart from it. Now virtually any board with capabilities beyond VGA might be called Super VGA.

TIFF. Tagged Interchangeable File Format. This bitmapped graphics standard is rapidly becoming the graphics equivalent of ASCII. Nearly all high-end graphics programs can export and import TIFF files.

VGA. Video Graphics Array. This advanced graphics adapter was introduced by IBM with its PS/2 line of personal computers. It's compatible with CGA, EGA, and MCGA. The adapter provides a wide assortment of display options, some of which are undocumented. Its highest resolution is 640 X 480 pixels, with 16 colors from a palette of 262,144.


dot-matrix. A dot-matrix printer is one that produces printouts by driving tiny hammers (called pins) against an inked cloth ribbon, leaving little dots on the paper beneath, from which graphics or text is formed on the page.

dpi. Dots Per Inch. This term is used to express the resolution of a printout from a laser printer. Most laser printers are able to print 300 dpi, though enhancements are driving high-end laser printers up against the lower limits of typesetting machines (1200 dpi). DPI is also used to describe the sensitivity of a mouse to movement. See also ppi.

DTP. DeskTop Publishing. DesTop publishing is a term coined by Paul Brainerd at Aldus to describe the ability of an individual to create a typeset page at his or her desk, thus marrying the job of editor, typesetter, layout artist, and printer. With so many responsibilities, the desktop publisher must have multiple skills because amateur efforts in any of these areas stand out even to the untrained eye.

font. Technically, a font is an individual typeface in a particular style and of a particular size. An example of a font is Times-Roman 12-point bold oblique. In computer and desktop publishing parlance, Times-Roman is often called a font. Owing to the magic of scalable outline fonts, an individual character can be changed almost infinitely is size from about 4 points to something in the hundreds of points, allowing variations of tenths or hundredths of points in between. Italic (or oblique) type, boldface, underscore, and several other variations are called typestyles. Purists are disdainful of these corruptions of the ancient language of typesetters.

ink-jet. Ink-jet printers spray an image on paper in tiny droplets of water-soluble ink. Though they are billed as producing printouts indistinguishable from those of laser printers, the tendency for the ink-jet nozzles to become clogged often results in telltale horizontal white lines through the image. Another drawback of ink-jet printers is the fact that the ink is susceptible to damage from moisture.

laser. Laser is an acronym standing for Light Amplification through Stimulated Emissions of Radiation. It's a very dense, concentrated light beam capable of crossing great distances with little degradation of power. Lasers are at the heart of much of the most exciting computer technology, and they may soon drive computers themselves. They are the power behind bar code readers that have affected our daily lives from the checkout counter at supermarkets to the recordkeeping technology at hospitals. Lasers have even been put to use in optical mice, laser printers, and hand scanners for importing graphic images. Laser printers use the laser beam to charge a light-sensitive coating on a drum in a manner similar to that of a photocopier. The drum is then exposed to charged toner particles that cling to the drum. Paper with an even greater electrical charge is moved past the drum, and the particles leap from the drum to the paper, which is then heaten to a temperature high enough to melt and bond the toner particles to the paper.

PostScript. PostScript is an interpreted computer language from Adobe Systems specially designed to make up pages, and thus it's known as a page-description language. When a page is created with PostScript, it's sent to the printer, not as a series of byte values to describe individual points on the page (which is how most graphics information is sent to printers), but as definitions of lines to be drawn, fonts to be used, and text to be printed in the specified fonts. These instructions are then interpreted by the printer and, through the hardware of a laser printer or typesetter, turned into a printer page.

ppi. Points Per Inch. Dissatisfied with the standard means of expressing a mouse's sensitivity to movement in terms of dots per inch (dpi), Microsoft invented points per inch. It means exactly the same thing: the number of discrete positions that the optical sensors inside the mouse can count through a mouse movement of an inch.

typeface. Technically, a typeface describes the appearance of a set of characters regardless of their size. Times-Roman 12-point and Times-Roman 14-point are different fonts in the same typeface. In computer and desktop publishing parlance, typeface and font are often used to refer to the same thing. The two most popular typefaces are Times Roman and Helvetica.

typestyle. Typestyle is a new expression created by desktop publishers to further describe the appearance of a font. Italic, boldface, shadow, outline, underline, super- and subscript, grayed, strikout, and plain are the standard typestyles.


AUX. Auxiliary. AUX is another way in DOS to refer to communications port 1 or COM1.

baud. Baud is a measure of the speed at which bits of information are sent or received over communications lines such as those used with a modem. Although the two don't mean the same thing, baud and bits per second (bps) are used interchangeably.

BBS. Bulletin Board System. A BBS offers a convenient way to communicate with fellow computer enthusiasts and acquire cop[ies of programs, picture files, and so on via a modem. The programs available on BBSs are usually shareware, which means you can try a program before you buy it.

COM. Communications. This is DOS device name used in connection with serial ports and is usually reserved for communications with a modem. There are, however, serial printers, for example, that must be connected to the computer through a serial port. To connect a serial printer to the computer, the MODE command is used to tell the system where to find the printer. With DOS 3.3 or higher, four communications devices may be specified on one system, COM1 through COM4.

CON. Console. CON refers to the keyboard and monitor. When you're using CON for input, it refers to the keyboard. For example, COPY CON > MYFILE.TXT copies everything you type at the keybard up until a Ctrl-Z and writes it to the file MYFILe.TXT. When used as output, CON refers to the screen. If you want to view the file you just created, you could view it with COPY MYFILE.TXT CON.

device. Any peripheral connected to a PC such as a mouse, printer, print buffers/spoolers, expanded memory boards, and so on can be called a device. You usually tell your PC's system about devices by installing device drivers in your CONFIG.SYS file.

device driver. Device drivers are essentially specialy TSRs that handle the input and output between peripherals such as printers or mice and the CPU of a computer. The standard device drivers include drivers for the keyboard, serial and parallel ports, and disk drives. You can install device drivers in your CONFIG.SYS file with lines that begin DEVICE=.

game port. Game ports are for joys-ticks, and joysticks are most beneficial when used with arcade games. The game port may allow the use of one or more joysticks. Some cards come equipped with a game port. Most game ports are the 15-pin variety.

LPT. Line PrinTer. This DOS device name specifies which port is used to connect a parallel printer to the computer. As many as three line printers can be installed on one system: LPT1, LPT2, and LPT3.

modem. MOdulator-DEModulator. A modem converts digital data to signals that can be transferred over audio transmission lines, most commonly phone lines. There are two types of modems, internal and external. An external modem must be connected to a serial port. An internal modem is a serial port and a modem combined.

mouse. A mouse is an input device that supplements the keyboard and was first used as a pointer in CAD, paint programs, and other graphics applications. The mouse's power and flexibility soon warranted its use in other environments such as database, spreadsheet, telecommunications, and desktop publishing. Most mice can be programmed for use with nonmouse applications.

NUL. Null. This is a DOS device used to hide output that usually appears on the screen. It can also be used with the CTTY command to hide all standard screen output during the execution of a batch file.

parallel port. Parallel ports allow your computer to connect to devices such as printers that use parallel interfacing. Usually, parallel ports send information from the computer to an attached device but don't receive information. A system with one parallel port recognizes the port as LPT1. Information is processed over eight wires, and each signal arrives at the printers at the same time (that is, in parallel).

PRN. Printer. This is another DOS device name used to refer to the printer connection. PRN can usually be used interchangeably with LPT.

RS-232. In 1969, the EIA (Electronic Industries Association) established a standard of communications between computers known as RS-232. Under this standard, an interface can have up to 25 wires connecting two devices. Most of the pins of wires have been assigned a function by the EIA standard. RS-232 is a serial standard, which means data bits are sent one after another. Devices that are connected with an RS-232 cable include external modems, mice, and serial printers.

serial port. A serial port lets you connect devices that communicate via a serial interface. Printers using an RS-232 cable are one example. Other serial devices include modems, mice, and optical character readers. Unlike parallel ports, serial ports normally send and receive information. One signal at a time is sent through the serial port, and the information is reassembled on the receiving end.